Cornwall III's and amp power

[xi-razorback]

Did a search and read a lot of good information on this and a lot of conflicting information too.

My concern is running a 250 WPC ss amp into the Cornwalls. Will I damage the speakers? My thoughts are that as long as I don't turn it up too loud they will be fine. Hell, wouldn't my ears explode before the speakers did? Cornwalls are being delivered Monday.

Currently have my Heresy III's hooked up to a 95WPC tube amp. Anxious to try it with the Cornwalls as well.

[wuzzzer]

If you aren't hearing audible distortion from the speakers you will be fine.

[StephenM]

My thoughts are that as long as I don't turn it up too loud they will be fine.

This is correct. Just because an amplifier can put out 250 watts per channel doesn't mean it actually is putting out 250 watts all the time.

Hell, wouldn't my ears explode before the speakers did?

In the end, it depends on how big your room is/how far you're sitting from your speakers and how much abuse you like dealing to your ears.

[mustang guy]

Welcome to the forum!

I would be careful here. 250 watts rms is way over the rating for these. I have 3 teenage sons, and I am not allways hovering over them. What you will do and what they will do is totally different. IMO, that tube amp will probably be as loud sounding as the 250 any way. Those speakers would sing better with tubes. Something like the McIntosh MC275.

[moray james]

I think that it is easier to blow a speaker with a smaller amp which is working well into distortion for prolonged periods of time than with a big am that does not distort or clip into the speakers. You have (the royal you) to learn what your speakers sound like loud and clean and what the speaker sounds like as it is entering into distortion and when it is in distress and it is time to back off. This kind of thing will vary from disk to disk so there is no way to say set a limit on the dial at which to stop. Owners and anybody who will be using the system have to learn its safe operation. When users are informed and understand the safe operating window then you can relax knowing that the system is being used properly no matter who is at the controls. One other point is that it has been my experience that people tend to turn up the dial to get more jam. So a good sub or two will go a long way in insuring that the users ears give up before the loudspeakers or the amp does.

One other observation I have made over the years is that a great number of people make a diredt association between distortion and loud playback level. This is understandable as there are so many systems which distort badly when turned up. The problem is that these people do not think a system is loud unless it is distorting. You have to teach people what loud clean music sounds like. A rat shak spl meter is a cheap way of showing people how loud they are listening. Once you have a good idea what 80db and 95 db sound like then you can better judge your own levels of playback. Better to have the meter and spend the time to establish these reference points than to deal with a damaged system.

I would rather my kids drive in a performance vehicle than an old beater which can get them into trouble just as fast but not get them out. Responsible behaviour is something that has to be shown taught and learned, sometimes the hard way. How many times does the lawn have to be cut to pay for a new woofer?

I suppose that if you were really concerned and you were willing to pay ther price of reduced fidelity you could install poly switches into the speakers which will disconnect them once a predetermined level is hit. Poly switches are thermal devices and once triggered they will trip more easily a second or third time. They require some time to cool and re establish the original threshold. So if you push the speakers will shut down and if you try pushing again the threshold starts to drop. Kind of gets peoples attention. Drawback is you do suffer reduced fidelity not bad but it`s there. My kids are grown one married the other still at home going to university. Neither has ever blown up any of my gear. My son at the age of three did find a way to make nice holes in my Acoustat 0ne plus 0ne`s with a popscicle stick. He showed me when I came home. My opportunity to act grown up and make it a learning experience. Some how he managed to reach all four panels. Funny thing was that it did not take much effort to forgive him and nobody got really upset. Good thing he did not stick his finger in there. Best regards Moray James.

[mustang guy]

I think that it is easier to blow a speaker with a smaller amp which is working well into distortion for prolonged periods of time than with a big am that does not distort or clip into the speakers. You have (the royal you) to learn what your speakers sound like loud and clean and what the speaker sounds like as it is entering into distortion and when it is in distress and it is time to back off. This kind of thing will vary from disk to disk so there is no way to say set a limit on the dial at which to stop. Owners and anybody who will be using the system have to learn its safe operation. When users are informed and understand the safe operating window then you can relax knowing that the system is being used properly no matter who is at the controls. One other point is that it has been my experience that people tend to turn up the dial to get more jam. So a good sub or two will go a long way in insuring that the users ears give up before the loudspeakers or the amp does.

One other observation I have made over the years is that a great number of people make a diredt association between distortion and loud playback level. This is understandable as there are so many systems which distort badly when turned up. The problem is that these people do not think a system is loud unless it is distorting. You have to teach people what loud clean music sounds like. A rat shak spl meter is a cheap way of showing people how loud they are listening. Once you have a good idea what 80db and 95 db sound like then you can better judge your own levels of playback. Better to have the meter and spend the time to establish these reference points than to deal with a damaged system.

I would rather my kids drive in a performance vehicle than an old beater which can get them into trouble just as fast but not get them out. Responsible behaviour is something that has to be shown taught and learned, sometimes the hard way. How many times does the lawn have to be cut to pay for a new woofer?

I suppose that if you were really concerned and you were willing to pay ther price of reduced fidelity you could install poly switches into the speakers which will disconnect them once a predetermined level is hit. Poly switches are thermal devices and once triggered they will trip more easily a second or third time. They require some time to cool and re establish the original threshold. So if you push the speakers will shut down and if you try pushing again the threshold starts to drop. Kind of gets peoples attention. Drawback is you do suffer reduced fidelity not bad but it`s there. My kids are grown one married the other still at home going to university. Neither has ever blown up any of my gear. My son at the age of three did find a way to make nice holes in my Acoustat 0ne plus 0ne`s with a popscicle stick. He showed me when I came home. My opportunity to act grown up and make it a learning experience. Some how he managed to reach all four panels. Funny thing was that it did not take much effort to forgive him and nobody got really upset. Good thing he did not stick his finger in there. Best regards Moray James.

My son drives an Impreza WRX. I am in your camp there. As for the amp compared to the speakers, they are $2,000 each speakers, and heating up a voice coil can degrade the expensive speaker over time. Then you are faced with the ever frequent question as to who dun it. If you got, or had, kids, you know what I mean there. If it were a 150 watt amp, I would not worry in the slightest. If it were a 250 watt per channel receiver I would worry a lot less. But if this is a regular amplifier it likely pumps out what it says. That is a full 150% over the rating of Klipsch. IMO, that's too much. Also, mods will possibly void the speaker warranty.

[xi-razorback]

I appreciate everyone's input. As I understand it, as long as the amp's volume control (really the preamp's volume control) is not turned up to a level that is more than the speakers can handle they will be fine. Or put another way, at a given sound level, a 250wpc amp will not heat up the voice coils any more than a 50wpc amp. Am I on the right track?

What good is a 250wpc amp anyway?

Oh, another thing I wanted to mention is the room is 25'x30' with 9 foot ceilings.

Thanks again.....

[moray james]

That sounds sensible to me. Do be aware that with a large clean amplifier you are likely to find yourself listening at higher levels overall as you will not be subject to the tell tail distortion limits found with a much smaller amplifier. If your speakers sound distorted they are so dial back the volume. That`s the reason that I mentioned the use of an spl meter which you can use to familarize yourself with the actual levels you listen at. A level of 95 db is about what you would expect to hear a band in a bar play at, normal conversation at normal distances will become difficult without getting much closer or without raising your voice. Your playback level (and so the power to the speakers) is set in combination by the setting on your preamp and the actual signal level of the source material. Extended listening at average levels of 95 db (for more than an hour) will cause your ears to ring.

If you are paying attention to the levels it is not likely that you would ever be peaking anywhere near the actual full output power of the amp into your speakers. For example ten watts continous full band would drive you from the room.

The larger the amplifier the greater the available head room so that even with a loud peak signal the amplifier will not clip on that peak. Larger amplifiers will also for the most part have larger more powerful power supplies and so you will minimize the potential of the supply clipping. With an amplifier you can clip either the supply and or ther output stage. You want to prevent either from happening. Solid state amplifiers have a tendency to clip much harder and more quickly than do tube amplifiers. Further the onset of clipping as well as the severity of clipping is more extreem with a Solid State amplifier. You will find that a tube amplifier will progress from rounding of the top and bottom of the signal soft and smoothly before eventually squaring the waveform off top and bottom. Tubes tend to clip gracefully and progressively Solid State just hit their limit and clip hard. Short bursts of peak clipping with a tube amp can and do go unnoticed because their duration is so brief and the amount of additional distortion is minimal. Solid state amplifiers can have your heart in your mouth in an instant as you rush to the volume controll. If by the way you have ever found yourself rapidly feeling as if emminent danger is at hand and you rush to turn things down this is because you were subjected to the onset of clipping. You will know it when you hear it. Most people have experienced this at one time or another. Now you know what it is. Don`t let your system go there and you will be fine, learn where the line is and simply do not cross it. Hope this helps best regards Moray James.

[mustang guy]

I appreciate everyone's input. As I understand it, as long as the amp's volume control (really the preamp's volume control) is not turned up to a level that is more than the speakers can handle they will be fine. Or put another way, at a given sound level, a 250wpc amp will not heat up the voice coils any more than a 50wpc amp. Am I on the right track?

Are you saying you would set the pre-amp at something like -8 db on those channels? That would reduce the resulting wattage getting to the speaker, by reducing the original signal wattage. Would the amp create more distortion doing that? I don't really know.

What good is a 250wpc amp anyway?

Not nearly as much good as high efficiency speakers. High output amps were invented when the speakers started to get smaller. The Cornwall III's are 102db speakers. At 100 watts, they output twice the spl as a 96 db speaker (every 6db is double the spl). Some consider a 96 db speaker high efficiency. It would take a 200 watt amp to make a mid 90's speaker as loud as the Cornwall III's can do at 100. Lastly, to double the perceived loudness of any speaker, you need to multiply the wattage by 10. To make a Cornwall III twice as loud as it is at 100 watts, you would need 1,000 watts.

Oh, another thing I wanted to mention is the room is 25'x30' with 9 foot ceilings.

That's a pretty good sized room. You could have dances.

[xi-razorback]

Thanks to all for your input. Yes, back in the day 250wpc was unheard of. Back then my 65wpc Kenwood integrated amp powering JBL Decades was a very nice system.

Anyway, thanks again to everyone who chimed in, I'll follow up after the Cornwalls arrive. Suppose to be here Monday. Can't wait................. I'm sure I'll be dancing.

[cubdog]

There is no reason your amp should cause any problem. You could use a 600 wpc amp without harming the speakers. You won't ever use that much power unless you put in earplugs and try to blow the Cornwalls up.

cubdog

[guitarman]

Agree with cubdog. One word....headroom.